Afferent influences: cell death in n. magnocellularis

发育中的动物神经元的存活通常依赖于传入活动。在后毛雏鸡中，第八神经活动的消失导致耳蜗核(NM)中20-40%的神经元死亡。决定单个NM神经元存活或死亡的因素在很大程度上是未知的。先前的研究表明，细胞死亡和细胞存活机制都竞争着决定单个细胞的命运。这项建议旨在研究去传入后激活的潜在细胞和分子级联反应。多项研究表明，bcl2家族成员参与了常见细胞死亡途径的调控。该基因家族既包括细胞“保护者”(bcl2和bclxl)，也包括“刽子者”(bax和bak)。我们将用原位杂交和免疫细胞化学的方法来检测去传入对促进生存的bcl2基因及其产物的激活和表达的影响。将进行更多的研究，以评估去传入对bcl-2家族其他成员的影响。例如，将研究促凋亡的bax与促生存的bcl2蛋白的差异表达。另一项研究将集中在bcl2基因下游被认为参与细胞凋亡的分子。线粒体的完整性是维持健康细胞的关键；线粒体生物能量学的损害会导致细胞色素-c的释放。胞浆细胞色素-c激活了通常所说的凋亡体。这种包括细胞色素-c、APAF-1和caspase-9在内的分子复合体将启动蛋白水解性caspase级联反应，最终导致细胞死亡。我们将结合免疫细胞化学和Western blotting技术来研究参与凋亡体的所有分子的传入调节。希望这项研究将阐明一些与去传入诱导细胞死亡有关的潜在机制。

Neuronal survival in developing animals is often dependent on afferent activity. In the posthatch chick, elimination of eighth nerve activity leads to the death of 20-40% of the neurons in the cochlear nucleus, nucleus magnocellularis (NM). The factors that determine whether an individual NM neuron will live or die are largely unknown. Previous studies indicate that both cell death and cell survival mechanisms compete to determine an individual cell's fate. This proposal seeks to examine the underlying cellular and molecular cascades that are activated following deafferentation. Several studies have implicated bcl-2 family members in the regulation of common cell death pathways. This gene family includes both cell "protectors" (bcl-2 and bcl-xL) and "executioners" (bax and bak). The effect of deafferentation on the activation and expression of pro-survival bcl-2 gene and gene product will be examined using both in situ hybridization and immunocytochemistry. Additional studies will be performed to assess the effect of deafferentation on other members of the bcl-2 family. For example, pro-apoptotic bax will be investigated for differential expression from the pro-survival bcl-2 protein. Another line of research will focus on molecules thought to participate in apoptosis downstream of bcl-2 genes. Mitochondrial integrity is pivotal to the maintenance of healthy cells; compromise of mitochondrial bioenergetics can result in the release of cytochrome-c. Cytosolic cytochrome-c activates what is commonly referred to as the apoptosome. This complex of molecules including cytochrome-c, Apaf-1, and caspase-9 will initiate proteolytic caspase cascades that ultimately lead to cell death. Afferent regulation of all the molecules involved in the apoptosome will be investigated through a combination of immuncytochemistry and Western blotting techniques. It is the hope that this research will elucidate some of the underlying mechanisms involved with deafferentation-induced cell death.